Makindo Medical Notes

Related Subjects: | AF - General | AF and Anticoagulation | AF and Rate Control | AF and Rhythm Control and Cardioversion | AF ECG | DC cardioversion

⚠️ Caution: haemodynamic compromise purely from AF is uncommon. More often the driver is the underlying illness (e.g. sepsis/pneumonia, ACS, PE, decompensated HF, electrolyte/metabolic derangement). Treat the precipitant first; if uncertain that AF is the primary problem, get senior/cardiology input early.

About

• ⚡ Any unstable tachyarrhythmia is an indication for synchronised DC cardioversion (DCCV).
• 🚑 If AF + life-threatening features → DCCV now (don’t delay for anticoagulation).
• 🫀 Synchronisation times the shock to the R wave to avoid “R-on-T” (VF risk).
• 🧠 Think “cause first”: in sinus tachycardia, don’t try to normalise HR with shocks/antiarrhythmics — treat the driver.

Life-threatening features (treat as UNSTABLE)

• 🫨 Shock
• 😵 Syncope with severe/ongoing hypotension
• 🫀 Myocardial ischaemia (ongoing chest pain/ECG ischaemia)
• 🌊 Severe heart failure with pulmonary oedema or shock
• 🧯 Immediately post-ROSC with recurrent/ongoing tachyarrhythmia

Emergency DCCV – Indications

• ⚡ Any tachyarrhythmia with life-threatening features.
• 💥 Fast AF with hypotension/ischaemia/pulmonary oedema (often HR >150/min) despite immediate supportive measures.
• 🧬 AF with pre-excitation (WPW physiology) and rapid ventricular response → DCCV or procainamide (avoid AV node blockers).
• 📈 VT with a pulse causing compromise → synchronised cardioversion.

Elective DCCV – Indications

• 🎯 AF as part of a rhythm-control strategy (symptoms, HF, first episode/early AF, patient preference).
• 🪽 Atrial flutter (often highly responsive to lower-energy DCCV).
• 🩸 Ensure an anticoagulation strategy (see below) or TOE-guided early cardioversion.

When Elective DCCV is Unlikely to Succeed / Consider Deferring

• 🕰️ Long-standing persistent AF (>12 months) or markedly enlarged LA (e.g. >5.0 cm / high LA volume).
• 🧯 Reversible trigger not corrected (infection, thyrotoxicosis, alcohol binge, pericarditis, severe valve disease).
• 🔁 Prior failed cardioversion despite optimisation/antiarrhythmics.
• 🩸 Not adequately anticoagulated (unless TOE strategy planned and no thrombus).

Anticoagulation Around Cardioversion (UK + practical)

• Scheduled/elective: if AF duration is >48 h or unknown (common UK threshold), give therapeutic OAC for ≥3 weeks before and ≥4 weeks after DCCV (DOAC or warfarin INR 2–3). Alternative: TOE-guided early cardioversion if no LA/LAA thrombus.
• Emergency/unstable: proceed with DCCV for instability, then start therapeutic OAC as soon as feasible and continue for ≥4 weeks (and long-term based on stroke risk).
• After 4 weeks: continue long-term OAC according to CHA₂DS₂-VASc / local policy, not “because they’re in sinus rhythm”.
• Pragmatic safety note: some contemporary guidance uses a more cautious >24 h threshold for “needs TOE or 3 weeks OAC before cardioversion” (especially if onset uncertain). If your history is shaky, treat it as unknown duration.

Procedure – Key Steps (DCCV)

• 👥 Senior review; call cardiology/anaesthetics if time allows; obtain consent where possible.
• 🫁 Sedation/anaesthesia with full monitoring (ECG, BP, SpO₂), IV access, airway kit ready.
• 🩹 Pad position: antero-posterior (or antero-lateral). Shave hair if needed; ensure firm pressure and good gel contact.
• 🔁 Select SYNCHRONISED mode for AF/SVT/VT with pulse; confirm sync markers before each shock.
• 🔥 Oxygen safety: keep O₂ source away from pad “spark zone”.

Energy (biphasic) – Practical starting points

• Narrow regular (SVT / typical flutter): 70–120 J (escalate if needed)
• Narrow irregular (AF): 120–150 J (then escalate to 200 J or per device)
• Wide regular (VT with pulse): start ~120–150 J (escalate)
• Wide irregular (polymorphic VT): DEFIBRILLATE (unsynchronised)

If DCCV fails (typical escalation)

• 🔁 Up to 3 shocks with escalation and optimised pad contact/position.
• 💊 Consider amiodarone 300 mg IV (then infusion e.g. 900 mg over 24 h) and repeat DCCV.
• 🧪 Re-check and correct K/Mg, acidosis, hypoxia, ongoing ischaemia, sepsis, PE etc.

Complications (risk–benefit)

• 🧠 Stroke/systemic embolism (risk minimised by correct peri-DCCV anticoagulation).
• 🐢 Post-shock bradycardia/pauses (usually transient; have atropine/pacing capability available).
• 🔥 Skin burns / myalgia at pad sites.
• 😴 Sedation-related events (hypoventilation, aspiration) — hence airway readiness.

Investigations (don’t delay emergency DCCV)

• 📈 12-lead ECG + continuous monitoring.
• 🧪 FBC, U&E, Mg²⁺, LFTs, glucose; TFTs if new AF or unexplained.
• 🫀 Troponin if ACS suspected; CRP/cultures/CXR if infection suspected.
• 🫁 Consider D-dimer/CTPA if PE suspected and clinically appropriate.
• 🧠 TOE if early cardioversion planned and not pre-anticoagulated (esp. duration >24–48 h or uncertain).

Images

References

• Resuscitation Council UK. Adult tachyarrhythmia algorithm (latest version).
• NICE NG196: Atrial fibrillation: diagnosis and management.
• ESC/EACTS AF guideline (latest).